diff --git a/core/modules/system/lib/Drupal/system/Tests/Database/ConnectionUnitTest.php b/core/modules/system/lib/Drupal/system/Tests/Database/ConnectionUnitTest.php
index cd72f26..522a60f 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Database/ConnectionUnitTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Database/ConnectionUnitTest.php
@@ -17,6 +17,8 @@ class ConnectionUnitTest extends UnitTestBase {
 
   protected $key;
   protected $target;
+
+  protected $monitor;
   protected $originalCount;
 
   public static function getInfo() {
@@ -34,18 +36,19 @@ function setUp() {
     $this->originalTarget = 'default';
     $this->target = 'DatabaseConnectionUnitTest';
 
-    // Retrieve current/original amount of connections.
-    $this->originalCount = $this->countConnections();
-  }
-
-  function tearDown() {
-    parent::tearDown();
-  }
-
-  protected function countConnections() {
-    return count(Database::getConnection()->query('SHOW PROCESSLIST')->fetchCol());
+    // Create an additional connection to monitor the connections being opened
+    // and closed in this test.
+    // @see TestBase::changeDatabasePrefix()
+    $connection_info = Database::getConnectionInfo('default');
+    Database::addConnectionInfo('default', 'monitor', $connection_info['default']);
+    global $databases;
+    $databases['default']['monitor'] = $connection_info['default'];
+    $this->monitor = Database::getConnection('monitor');
   }
 
+  /**
+   * Adds a new database connection info to Database.
+   */
   protected function addConnection() {
     // Add a new target to the connection, by cloning the current connection.
     $connection_info = Database::getConnectionInfo($this->key);
@@ -57,21 +60,50 @@ protected function addConnection() {
     $this->assertIdentical($info[$this->target], $connection_info[$this->key], 'New connection info found.');
   }
 
-  function testNoop() {
-    // Verify that retrieving the amount again does not increase it.
-    $this->assertIdentical($this->countConnections(), $this->originalCount);
+  /**
+   * Returns the connection ID of the current test connection.
+   *
+   * @return integer
+   */
+  protected function getConnectionID() {
+    return (int) Database::getConnection($this->target, $this->key)->query('SELECT CONNECTION_ID()')->fetchField();
+  }
+
+  /**
+   * Asserts that a connection ID exists.
+   *
+   * @param integer $id
+   *   The connection ID to verify.
+   */
+  protected function assertConnection($id) {
+    $list = $this->monitor->query('SHOW PROCESSLIST')->fetchAllKeyed(0, 0);
+    return $this->assertTrue(isset($list[$id]), format_string('Connection ID @id found.', array('@id' => $id)));
+  }
+
+  /**
+   * Asserts that a connection ID does not exist.
+   *
+   * @param integer $id
+   *   The connection ID to verify.
+   */
+  protected function assertNoConnection($id) {
+    $list = $this->monitor->query('SHOW PROCESSLIST')->fetchAllKeyed(0, 0);
+    return $this->assertFalse(isset($list[$id]), format_string('Connection ID @id not found.', array('@id' => $id)));
   }
 
   /**
-   * Tests Database::closeConnection().
+   * Tests Database::closeConnection() without query.
+   *
+   * @todo getConnectionID() executes a query.
    */
   function testOpenClose() {
     // Add and open a new connection.
     $this->addConnection();
+    $id = $this->getConnectionID();
     Database::getConnection($this->target, $this->key);
 
     // Verify that there is a new connection.
-    $this->assertIdentical($this->countConnections(), $this->originalCount + 1);
+    $this->assertConnection($id);
 
     // Close the connection.
     Database::closeConnection($this->target, $this->key);
@@ -79,19 +111,20 @@ function testOpenClose() {
     usleep(20000);
 
     // Verify that we are back to the original connection count.
-    $this->assertIdentical($this->countConnections(), $this->originalCount);
+    $this->assertNoConnection($id);
   }
 
   /**
-   * Tests Database::closeConnection().
+   * Tests Database::closeConnection() with a query.
    */
   function testOpenQueryClose() {
     // Add and open a new connection.
     $this->addConnection();
+    $id = $this->getConnectionID();
     Database::getConnection($this->target, $this->key);
 
     // Verify that there is a new connection.
-    $this->assertIdentical($this->countConnections(), $this->originalCount + 1);
+    $this->assertConnection($id);
 
     // Execute a query.
     Database::getConnection($this->target, $this->key)->query('SHOW TABLES');
@@ -102,19 +135,20 @@ function testOpenQueryClose() {
     usleep(20000);
 
     // Verify that we are back to the original connection count.
-    $this->assertIdentical($this->countConnections(), $this->originalCount);
+    $this->assertNoConnection($id);
   }
 
   /**
-   * Tests Database::closeConnection().
+   * Tests Database::closeConnection() with a query and custom prefetch method.
    */
   function testOpenQueryPrefetchClose() {
     // Add and open a new connection.
     $this->addConnection();
+    $id = $this->getConnectionID();
     Database::getConnection($this->target, $this->key);
 
     // Verify that there is a new connection.
-    $this->assertIdentical($this->countConnections(), $this->originalCount + 1);
+    $this->assertConnection($id);
 
     // Execute a query.
     Database::getConnection($this->target, $this->key)->query('SHOW TABLES')->fetchCol();
@@ -125,19 +159,20 @@ function testOpenQueryPrefetchClose() {
     usleep(20000);
 
     // Verify that we are back to the original connection count.
-    $this->assertIdentical($this->countConnections(), $this->originalCount);
+    $this->assertNoConnection($id);
   }
 
   /**
-   * Tests Database::closeConnection().
+   * Tests Database::closeConnection() with a select query.
    */
   function testOpenSelectQueryClose() {
     // Add and open a new connection.
     $this->addConnection();
+    $id = $this->getConnectionID();
     Database::getConnection($this->target, $this->key);
 
     // Verify that there is a new connection.
-    $this->assertIdentical($this->countConnections(), $this->originalCount + 1);
+    $this->assertConnection($id);
 
     // Create a table.
     $name = 'foo';
@@ -165,7 +200,7 @@ function testOpenSelectQueryClose() {
     usleep(20000);
 
     // Verify that we are back to the original connection count.
-    $this->assertIdentical($this->countConnections(), $this->originalCount);
+    $this->assertNoConnection($id);
   }
 
 }